METALLURGY OF IRON AND STEEL.
point which can be determined more accurately than the reduction of area, and nearly as accurately as the elongation. If a new point is desired, such as shown'by an autographic device, then this new
TABLE XYIII-B. Calculation of 12.0 V / ^or Different Diameters.
m i fi 'a
<o rg M 5« Mm 3 '
Cg wg H rj — "^
." 0< Q? . — < MO^
IH" CD fl goJ JT 7 ° ^•« *fl °?-! °Ss^ -Sp-aOQ Ovt 01 .rS
| o ">'Sf ® e> « fi • o 9 5 g bb
«l-l o5 ®'M ft SS ftcfe
fl < 9 fr*
^ .1968 .443 5.82 83.2
% .8067 .554 6.65 81.5
§4 .4417 .665 7.98 80.2
j2 .6018 .775 9.80 29.8
1 .7854 .886 10.63 28.7
1J"6 .9940 .997 11.96 27.8
!xl 1.2271 1.108 18.80 27.1
point should be given a new name. The term "elastic limit" has been preempted, by general use, as part of a system of trade nomenclature to designate the point where the beam drops.
Upon this determination all specifications and contracts are based, and any attempt to ascertain the elastic limit in any other way is a change in the contract requirements which would not be sustained in a court of equity. All calculations upon factors of safety in existing bridges are .based upon this "drop of the beam," and there seems to be no good reason why one arbitrary point should be substituted for another and no reason why future work should not be carried on under the present established and well-understood system.
SEC. XVIIIf.—The quench-test.—In regard to what is known as the quench-test, I am of the opinion that it is, an absurdity when applied to ordinary structural material. It was defended by Mr. Hunt* on the ground that it would guard against careless heating and cooling in the mill or shops, but this suggests the query why such carelessness should be tolerated. It is assumed that the work is done by mills and shops that understand their business, and the steel should be made to fit the work in hand and not the ignorance of middlemen. It is right to make severe tests on the cold proper-
* The Inspection of Materials of Construction in the United States. Journal I. and 8. I., Vol. II, 1890, p. 312.